Antibiotics - Nucleic Acid Inhibitors

Question 1

Name some types of nucleic acid inhibitors.

Answer 1

Fluoroquinolones, fidaxomycin, rifamycin, metronidazole

Question 2

What are some examples of fluoroquinolones?

Answer 2

Ciprofloxacin, moxifloxacin

Question 3

Mode of action for fluoroquinolones?

Answer 3

Inhibit DNA gyrase (we have a different one so it’s fine)

Question 4

Resistance for fluoroquinolones?

Answer 4

Altered DNA gyrase, drug exclusion

Question 5

Uses for fluoroquinolones?

Answer 5

Not very soluble, so fluoronation helps vs. UTIs and other G-/G+ infections, including Mycobacteria (2nd line) and Pseudomonas

Question 6

Side effects of fluoroquinolones?

Answer 6

Prolonged QT interval (Torsades de Pointes)

Question 7

Mode of action for fidaxomycin (Dificid)?

Answer 7

Targets “switch region” (loading clamp) of RNAP and prevents interaction of RNAP with DNA

Question 8

Uses for fidaxomycin (Dificid)?

Answer 8

Alternate to vancomycin for C. diff colitis

Minimal absorption and narrow spectrum means (hopefully) less selection for resistance.

Question 9

Mode of action for rifamycin?

Answer 9

Blocks RNA polymerase elongation subunit

Question 10

List some types of rifamycin.

Answer 10

Rifampin, rifabutin, rifaximin

Question 11

Uses for rifamycin?

Answer 11

With isoniazid to delay resistance in Mycobacteria

• Crosses CNS (meningitis treatment)
• Blocks assembly of poxviruses

Question 12

Side effects of rifamycin?

Answer 12

Excreted in sweat and urine (turns it orange!)

Question 13

Mode of action for metronidazole?

Answer 13

Partially reduced complex with ferredoxin interacts with DNA and breaks DNA strands (free radical)

Question 14

Uses for metronidazole?

Answer 14

Antiprotozoal (Giardia) and vs. anaerobic (Bacteriodes, Clostridium)